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Can Heat be Used to Control the Speed of a Motor?
Table of Contents
Problem Scenario
This is a useful experiment because it involves motors and how heat can affect them because motors in cars heat up gradually and lose their effectiveness.Broad Question
Can You Control the Speed of a Motor?Specific Question
Can Heat be Used to Control the Speed of a Motor?Hypothesis
The Higher the Temperature the Slower the Speed of the MotorHypothesis Chart
Variables
Independent Variables: 9 Volt Battery, 24,000 RPM MotorDependent Variable: Temperature in Celsius
Variables That Needs To Be Controlled: 9 Volt Battery, 24,000 RPM Motor
Vocabulary List
Thermister: A variable resistor that changes it's resistance.RPM: RPM stands for Revolutions per Minute, which means every minute the motor spins a certain amount when at max speed.
LCD: LCD stands for Liquid Crystal Display. An LCD is a basic display that displays numbers and letters.
Tachometer: A tachometer is a tool used for measuring the speed of a motor in RPM.
PWM: PWM, or Pulse Width Modulation changes the wavelength of the current to provide different amounts of power to the motor.
General Plan
I will be testing the speed of a motor three times for six different temperatures. I will sample the speed of the motor and record the data in a Google Docs Spreadsheet.Problems And Solutions
The first problem I might have is that the battery connection might break so I will add capacitors to store some energy in case of power losses. The second problem is that the temperature might not be accurately measured so I will use an Arduino to make a thermometer with an LCD. The third problem is that the motor might short so I might have to add a resistor.
Safety or Environmental Concerns
One problem is that the thermistor might blow so I will check what the maximum heat rating is and adjust accordingly. The second problem is that the LCD thermometer might not work so I will find the correct formula to get the temperature correct so that I won't blow the thermistor. The last problem I might have is that the motor might not have enough power so I might add a transistor to amplify the current.Experimental Design
What is your experimental unit?
The speed of a motor in RPM.Number Of Trials:
I will test my experiment three times for every temperature.Number Of Subjects In Each trial:
2, the temperature and the speed of a motor.Number of Observations
I will take a test of the RPM 3 timesWhen data will be collected
February 27thWhere will data be collected?:
Data will be collected on my floor because it is stable.Resources Table
Detailed Procedure
1. Connect the power (+) and ground (-) of a 9 Volt battery to the thermistor and motor.2. Test the RPM of the motor to make sure it is at full speed.
3. When the motor is at max speed apply 60°C to the thermistor and check the RPM.
4. After the first test apply 50°C to the thermistor and check the RPM.
5. After the second test apply 40°C to the thermistor and check the RPM.
6. After the third test apply 30°C to the thermistor and check the RPM.
7. After the fourth test apply 20°C to the thermistor and check the RPM.
8. After the fifth test apply 10°C to the thermistor and check the RPM.
9. After the sixth test apply 0°C to the thermistor and check the RPM.
Diagram
Photo List
Time Line
Data Table
Data Analysis
All Raw Data
See above table.Graphs
Photos
The code
A tachometer
The LCD displayThe motor control setup without the LCD display.
Results
At 60 degrees the motor was considerably faster than the other temperatures, the maximum speed being 16,000 RPM. At 50 degrees the motor slowed down about 5,000 RPM (to an average of 8,666 RPM). At 40 degrees the motor slowed down about 2000 RPM (to an average of 6,020 RPM). At 30 degrees the motor slowed down about 6000 RPM (to an average of 1,130 RPM). The motor stopped at 20 degrees and below because there wasn't enough heat to run the motor.
Conclusion
Can heat be used control the speed of a motor? Yes, heat can be used to control the speed of a motor. At 60 degrees the motor was considerably faster than
the other temperatures. At 50 degrees the motor slowed down about 5000 RPM. The motor continued to slow down until the temperature was at 20 degrees when the RPM went to 0.
Discussion
The data revealed that that my hypothesis was incorrect. The experiment showed that the motor goes faster as the temperature increases. The three sets of data collected showed that the motor speed actually increased with an increase in temperature. The variables that were chosen worked well with this experiment and the speed of the motor changed drastically with a rise in temperature. I was able to answer the experiment question with the methods that were used. During data collection at low temperatures(0-20 degrees celsius) this setup did not provide enough voltage to power the motor. This experiment could be advanced by replacing the thermistor with a more accurate thermistor or thermal probe and the program could be fine tuned to expand the data set.Benefit to Community and/or Science
This experiment could help the community in many ways involving transportation. The experiment could be used to control coolant use in engines or motors to use the coolant more effectively. This experiment could help vehicle-owners become more efficient and pay less. Another application for this experiment would be house heating. A thermistor could control the speed of a fan to circulate heat more efficiently.Background Research
This project was workable with my existing knowledge but I did have to do some intermediate research on how to use the transistor to amplify the current from the Arduino. I used a NPN transistor that amplified the current coming out of the Arduino. The transistor was helpful because the pins on the Arduino do not provide enough current so it uses it's ability to amplify the power. I also had to use the datasheet provided by the thermistor manufacturer to find out the resistance at certain temperatures.
The Arduino uses Pulse Width Modulation to take the signal from the thermistor and convert it to a range of 0-255. This conversion allowed the motor to be controlled more precisely.
The way thermistors work is that they create a larger resistance for a small temperature change. In the head of a thermistor there are several layers of small electrodes, which are connected by semi-conducting materials. These materials create resistance to the electricity being run through the thermistor, causing it to react to the heat from the electricity.
To use the motor I had many other designs before I found the transistor design. My original design was just hooking up the thermistor to the positive end of the motor and the negative end to ground on the nine volt battery. That did not work very well because the thermistor that I was using did not have enough resistance in it to vary the speed of the motor adequately.
The LCD display was easy to use because of the tutorial on the Arduino website. I just made a few edits to the code and added a conversion used to find the temperature of a thermistor. I was able to do a project that I was interested in so it was a lot of fun, but a little more complicated than I expected.
References
"JeremyBlum.com." JeremyBlum.com. N.p., n.d. Web. 13 Mar. 2013."Arduino - LiquidCrystal." Arduino - LiquidCrystal. N.p., n.d. Web. 13 Mar. 2013.
Monk, Simon. 30 Arduino Projects for the Evil Genius. New York: McGraw Hill, 2010. Print.
Abstract
Who doesn't, at some point in their point in their life, use a motor? I decided to research the effect of temperature on the speed of a motor. I thought that as the temperature applied to the motor increases, the speed of the motor decreases. To test this hypothesis, I programmed an Arduino microcontroller to change the speed of a 24,000 RPM motor proportionally to the temperature applied to the temperature sensor. I then measured the RPM of the motor with a tachometer to verify the exact speed. I put the variable resistor into 7 different cups of water, ranging from 0 degrees Celsius to 60 degrees Celsius, to see how the change in temperature affected the speed of a motor.In this experiment I learned that the higher the temperature applied to the motor, the faster the speed of the motor. While doing this project I also learned some uses of Arduino, like motor control. I discovered that when temperature applied to a thermistor increases, so does the speed of a motor connected to it.